Motor control system



Aug. 16, 1938.

C. H. RAMSEY MOTOR CONTROL SYSTEM 4 Sheets-Sheet 1 Filed Feb. 5, 1935 INVENTOR, 9mm :2,

ATTORNEY.

Aug. 16, 1938. c. H. RAMSEY MOTOR CONTROL SYSTEM Filed Feb. 5, 1955 4 Sheets-Sheet .2

ATTORNEY.

Aug. 16, 1938.

C. H. RAMSEY MOTOR CONTROL SYSTEM Filed Feb. 5, 1955 4 Sheets-Sheet 3 INVENTOR Clay/0 rd. /7- 9am y ATTORNEY.

Aug. 16, 1938. c. H. RAMSEY MOTOR CONTROL SYSTEM Filed Feb. 5, 1935 4 Sheetsfiheet 4 m M M p a, a C

ATTORNEY.

Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE 4 Claims.

In certain machines, as the so-called Palmer machine, an endless quite thick flexible blanket of considerable Width and longitudinal extent is made to travel around a drum of relatively large 5 diameter, and perhaps also around a drum of smaller diameter, as well as around suitable guides, the blanket performing some such service as maintaining between itself and the large drum a fabric undergoing some treatment and which travels with the blanket.

On account of the considerable length, width and thickness and other qualities of the blanket it is found in practice that the blanket skews one way or the other in its passage through the machine which of course gives rise to certain troubles in respect to the fabric being treated, not to mention distortion of and injury to the blanket from edgewise contact with parts of the machine and otherwise.

I aim by this invention to overcome this fault, having in mind that this shall be accomplished entirely automatically in the preferred form of the invention.

According to the invention, given means to 25 maintain a travelling blanket or equivalent flexible sheet more or less taut, there is a director, extending transversely of the path of travel of the sheet, which maintains a slight or at most a quite obtuse bend therein and which is pivoted at a point lateral of at least the median longitudinal line of the sheet (but preferably lateral of the sheet itself) so as to be angularly displaceable in a plane extending generally lengthwise of the travel of the sheet. I have found that if this director be moved in said plane around its pivot it counteracts the skew so that at least the skew may be terminated if the director does not actually cause the blanket to skew from its intended path in the opposite direction.

In putting this director to practical use I provide means to move it in the appropriate direction including a motor. In respect to the automatic actuation of the director there is a switch movable from a neutral position, in which the energy is cut off from, to a position in which it directs energy to, the motor, and there is an electric circuit, including an ele'ctro-magnetic means to move the switch to and hold it in its new position, which is adapted to be closed by the sheet when it skews to energize and thereupon to be interrupted by the director-moving means to deenergize such means. It is found that the director when shifted to terminate the skew usually imparts to the sheet a counter skew, wherefore a motor of the reversible class is used; the switch is of the class which is movable from the neutral position to either of two positions in one of which it directs forward-driving energy and in the other reverse-driving energy to the motor; the electromagnetic means is duplicated and they are oppositely acting; and the circuit arrangement is such that on the sheet skewing in either direction the appropriate one of said electro-magnetic means will be first energized and then de-energized substantially in the manner already stated.

In the drawings,

Fig. 1 is a side elevation of a Palmer machine embodying the invention;

Fig. 2 is a view as seen from the left in Fig. l of the angularly displaceable director B and the means by which its displacement is effected;

Fig. 3 is a section on line 33, Fig. 2;

Fig. 4 is an enlarged elevation of what is shown in Fig. 2, viewed the same as in Fig. 1;

Figs. 5 and 6 are sections on line 55 and 66, respectively, Fig. 4;

Fig. '7 shows what I term the detector-controller for said means, as viewed from the right in Fig. 1, and Fig. 8 is a vertical sectional view thereof;

Fig. 9 is a diagram of the electric system with parts L'L2 in the positions they tend to assume independently of the hereinafter-mentioned carrier; and

Fig. 10 a diagram illustrating how the shifting of the director B controls the travel of the blanket, the view being as from the left in Fig. 1.

Let I be the frame of a Palmer machine here shown having the usual large drum 2 and also the smaller drum 3 journaled therein on parallel horizontal axes. The endless blanket A is trained over a guide 5 at the right, around the drum 2, then around a guide 6 above and near to guide 5, then over a guide I, and then in succession around an adjustable take-up guide 8, the smaller drum, the guide 8a and the axially displaceable member B (to be described), and finally around the guides 9 and I8. As usual the cloth to be treated is entered at the space between the guides 5 and 6 and then passes around and over the drum 2 between it and the blanket.

The director may be as follows: A shaft H on L which may be rotative any suitable roller l3 (Fig. with which the blanket has direct contact has one end telescoped so as to slide in a sleeve l4 pivoted in the frame by means of its horizontal stud Ma, its other end having aflixed thereto a sleeve I5.

The means to displace the director around its pivot at Ma is as follows: Sleeve I5 is pivoted on a pin l6 (parallel with stud Ma) in the fork lla of a nut ll movable up and down. The structure I l--|3--|5 is quite heavy, wherefore after it has been fitted to sleeve [4 an underneath lug a of sleeve I5. is rested in the recess lfla of a saddle member 18, which is bolted between the arms of the fork, until pin l6, which has a tapered end, can be entered to form the pivot between sleeve I5 and the nut and then secured by a thumbscrew l9 (Figs. 2 and 3). The supporting structure includes, with the frame, upper and lower brackets --2|, the latter comprising a housing 2la. In bracket 20 and the lower part of the housing is journaled a screw 22 with whose threading the nut is engaged. Bracket 2| supports a reversible three-phase alternating-current electric motor M whose armature is adapted to drive the screw in either direction through any suitable reduction-gear system such as is illustrated at 24. The nut has a fork 25 (Fig. 6) projecting toward frame I which straddles a vertical fixed shaft 26, thereby preventing the nut from rotating around the screw; to eliminate the friction between the nut and shaft incidental to the torque acting on the nut while rising the latter may have a roller 21 to bear on the shaft. Parts 28 projecting from the nut afford sleeves which are penetrated by vertical rods 29-30 each of which is vertically adjustably held in its sleeve by a set-screw 3|. It is assumed in the example that the forward drive of the motor turns the screw anti-clockwise (viewed in plan), thus to raise the carrier formed by the nut and the rods and the right-hand end of director B.

With reference, now, to the control of the described means for displacing the director B.

In the movement of the carrier its rods effect alterations in the positions of circuit-closers or circuit-closing devices, which I term limit switches, L and L2 of an electric circuit, each of which switches is pivoted at 32a in a box 32 affixed to bracket 2|. That is, limit switch L is normally urged to closed position and limit switch L2 to open position (which may be by springs, not shown), but the rods 29 and are adapted to move limit switch L to open position when the carrier rises and allow limit switch L2 to assume closed position when the carrier descends; otherwise stated, the rods form actuating devices for the switches when the actuator rises. The carrier in Fig. 2 is then in that position in which shaft H is horizontal, switch L being in its normal (closed) position and switch L2 being held closed. Upward movement from such position will open switch L (L2 remaining closed) and downward movement from such position will allow switch L2 to open (L remaining closed).

The system comprising the director B, the carrier and its means for shifting it, and the limit switches is placed at that point in the circuit of the endless blanket which is most remote from the guides 5-6, or at a point where the skewing of the blanket would begin to manifest itself appreciably and where at the same time the correction of its travel may be best effected before it returns to the larger drum. However, I do not wish to be limited to this particular location.

At a point relatively near where the blanket leaves this drum the detector-controller C is placed. Thus, Figs. 1, '7 and 8, on a shaft 33, forming with the frame a part of the fixed structure of the machine, is mounted a box 34 in which is pivoted at 35 a pendant 36 having a depending blade 36a arranged to flank the blanket and equipped with a mercury switch here consisting of a glass bulb 31 having three depending hollow legs 31a into which reach terminals of the controlling circuit, 38 (Fig. 9) indicating the level of the contained mercury when the blade is per pendicular or such switch (the blanket being in its mean position) is in neutral position so that only the middle terminal is contacted by the mercury. Since pivot 35 is offset to the side of the blade toward the blanket gravity tends to hold the detector-controller against the edge of the blanket as it skews away from the blade; and the latter may, in skewing in the opposite direction, displace the detector-controller in such direction.

In the diagram Fig. 9 let 39- be the main or service lines to the motor. There is a switch for these lines comprising two oppositely acting solenoids whose cores Alla- WD form circuit-closers for said lines, 4la4lb being the solenoid coils; when circuit-closer 40a is in closing position the motor will be driven forward, and when circuitcloser 40b is in closing position the motor will be H driven reversely, as is well known. The switch is normally held by gravity acting on the circuitclosers in neutral position, or so that the energy is cut off from the motor.

The controlling circuit consists of a lead 42 extending from one of the service lines 39 to the mercury switch, affording its middle terminal, being then divided to form branches 42al2b each affording one of the other two mercury switch terminals and respectively containing the limit switches LL2 and the solenoid coils Ma 4Ib, lead 42, after the merging together again of its branches continuing to one or the other two service lines.

Operation.--The description of the operation will be predicated on the circumstance that if the director B be shifted to position a or to position b Fig. 10 the blanket will be directed or skewed in the direction of the corresponding arrow, or generally in a direction perpendicular to member B when in such position.

On movement of the carrier downwardly limit switches L--L2 are permitted by the carrier rods 29-40 respectively to assume circuit-closing and circuit-opening relation, and on movement of the carrier upwardly such switches are caused by the rods respectively to assume circuit-opening and circuit-closing relations. Hence, if after each such movement the circuit be completely closed through the branch having the thus-closed limit switch the motor will be driven forward and reversely alternately and so move the carrier and hence director B back and forth. This duty is performed by the detector-controller C, subject to the influence of the blanket. The adjustment of the rods 293l3 vertically determines the extent of movement of the carrier, to wit, the active period (forward or reverse) of the motor. Thus it might be possible to reciprocate the carrier through the whole extent available, i. e., between brackets 20--2 l, to wit, by depressing rod 29 and elevating rod 30 to an appropriate extent. Or it is possible to reciprocate the carrier through a range of any desired length and constituting any part of the whole extent available, for instance, from the position shown in Fig. 2 (director B horizontal) up or down any part of the available distance.

Suppose the blanket is disposed to skew to the right, viewed from the left in Fig. 1. The rods are then set so that the range of movement of the carrier will be from a position more or less approximating the mean to some higher position, depending on the degree of the skew. When the blanket, in passing through the machine,

skews to the right the detector-controller C closes (by its mercury switch) the branch 42a of the controlling circuit, thereby actuating the motor switch to close the service lines for forward driving of the motor, which in turn effects tilting of director B toward position a, the carrier by its rod 29 in time moving limit switch L to open position to de-energize the controlling circuit and allow the motor switch to resume its normal position, cutting off the energy to the motor. A compensating skew to the left is, by the tilting of director B, imparted to the blanket. Limit switch L2 now stands closed, and when the blanket skews sufiiciently to the left the detectorcontroller moves to close the branch 421), whereupon a series of operations will ensue as before.

The operator should adjust the rods with respect to the degree of skew which the blanket is disposed to assume. Thus, if the blanket has but little disposition to skew but the rods are set for considerable skew the motor would be operating through unduly long periods, and since the pitch attained by the director B would be undue the blanket would be caused to oscillate laterally at unduly frequent intervals, with corresponding shortening of the idle periods of the motor. On properly setting the rods, after running the blanket a while to determine the degree of the skew it is disposed to manifest the active periods of the motor will be shortened and (because the pitch attained by member B is less) its idle periods lengthened.

In the example the blanket or other sheet travels in contact with two supports (as 8a and 9) and the director, arranged between these supports and maintaining a slight bend in the sheet, is displaceable as indicated in a plane extending generally lengthwise of the travel of the sheet. However, so far as the means to displace the director is concerned my invention is not limited to the degree of bend it maintains in the sheet nor to its displacement in such plane.

For the purposes of this disclosure I term the breaks between the lead 42 and its branches and adapted to be closed by control or switch C primary breaks and the breaks in the branches adapted to be closed by circuit closers L-L2 secondary breaks.

Having thus fully described my invention what I claim is:

1. The combination, with a back-and-forth movable system including a reversible motor, switch elements one of which is movable to direct forward-driving and the other of which is movable to direct reverse-driving energy to the motor, and an electric circuit including branches each having a primary and a secondary break therein and means in the branches to control the movements of the respective switch elements, of means to close the primary break in one branch when the motor is to be driven forwardly and the primary break in the other branch when the motor is to be driven reversely, and devices for closing the secondary breaks in the respective branches one of which is normally urged to closed and the other of which is normally urged to open position, said devices being arranged to be respectively moved to open and closed positions by said system when the latter is moved in one direction.

2. The combination, with a back-and-forth movable system including a reversible motor, switch elements one of which is movable to direct forward-driving and the other of which is movable to direct reverse-driving energy to the motor, and an electric circuit including branches each having a primary and a secondary break therein and means in the branches to control the movements of the respective switch elements, of means to close the primary break in one branch when the motor is driven forwardly and the primary break in the other branch when the motor is driven reversely, and devices for closing the secondary breaks in the respective branches one of which is normally urged to closed and the other of which is normally urged to open position, said system when removed from one of its limits holding said devices respectively in their open and closed positions and when moved toward said limit being adapted to free said devices.

3. The combination, with supporting means, a reversible motor, a back-and-forth movable means connected with the motor to move back and forth, switch elements one of which is movable to direct forward-driving and the other of which is movable to direct reverse-driving energy to the motor, and an electric circuit including branches each having a primary and a secondary break therein and means in the branches to control the movements of the respective switch elements, of devices for closing the secondary breaks in the respective branches one of which is normally urged to closed and the other of which is normally urged to open position, actuating devices adapted, when the second-named means moves in one direction, to move the firstnamed devices to open and closed positions, respectively, and means to close the primary break in one branch when the motor is to be driven forwardly and the primary break in the other branch when the motor is to be driven reversely, the first-named devices being arranged on one and the second-named devices being arranged on the other of the first two means and those which are arranged on one being adjustable toward and from the devices which are arranged on the other of said first two means.

4:. The combination, with supporting means, a reversible motor, a back-and-forth movable means connected with the motor to move back and forth, switch elements one of which is movable to direct forward-driving and the other of which is movable to direct reverse-driving energy to the motor, and an electric circuit including branches each having a primary and a secondary break therein and means in the branches to control the movements of the respective switch elements, of devices carried by the first-named means for closing the secondary breaks in the respective branches one of which is normally urged to closed and the other of which is normally urged to open position, other devices carried by the second-named means and arranged to hold the first-named devices in open and closed positions, respectively, when the second-named means stands removed from one of its limits and to release the first-named devices when said second-namedmeans is moved toward its other limit, and means to close the primary break in one branch when the motor is to be driven forwardly and the primary break in the other branch when the motor is to be driven reversely, the devices carried by one of said means being adjustable thereon toward and from the other devices.

CLIFFORD H. RAMSEY. 

